In fabricating packaging strips, preferably press-through packages which are made from a strip of foil comprising a lower foil strip with depressions for receiving tablets, lozenges or the like, and a foil cover strip which closes the depressions and is combined with the lower foil strip by heat-sealing, it is very important that the desired individual package units be stamped out with very little trimming waste, or in any event with as little waste as possible. A so-called "waste-free stamping operation" is performed by making the trailing edge of one packaging strip the leading edge of the next packaging strip when the foil strips are separated. Thus nothing is wasted between the individual packaging strips. A further requirement for such packaging strips is that the corners of the packaging strips must be rounded. This is very important in the further processing of these packaging strips, because otherwise it becomes difficult to insert such packaging strips into cardboard boxes or the like. Furthermore, packages lacking rounded corners would present the danger of injury both to the worker processing them and, especially, to the final consumer for whom the package is intended.
For various reasons, for example a change in the foil as it passes through the processing machinery or shrinkage of the foil, particularly while the machinery is stopped, there is always a slight nonuniformity in the advancement of the foil strips, so that it is impossible to effect the stamping cut with the desired degree of exactness. In consequence, the stamping cut for the front edge of one package strip may not be located precisely at the stamping cut made earlier for the immediately previous packaging strip. As a result, sharp, hooklike protrusions are created in the vicinity of the round corners at the front of a packaging strip, viewed in the direction in which the strip is advanced; as would also be the case with packaging strips not having rounded corners, this phenomenon can cause interruptions in the further processing steps and are a possible cause of injury.
In order to prevent sharp protrusions of this kind, it has already been proposed in (Japanese Patent Application No. 55/45360) that packaging strips be fabricated by a method such that the forward corners in the direction of advancement have a different arcuate radius from the rear corners. As is particularly shown in FIG. 4 of this Japanese patent application, the intention is thereby, at the overlap of the arcs of different radii, to prevent the sharp protrusion that would otherwise be created where arcs of equal radii intersect. However, it has been found that with this kind of procedure it is not possible to eliminate sharp protrusions completely; with this method, the sharp protrusions produced by earlier known methods can only be diminished somewhat. Furthermore, packaging strips having rounded corners of unequal radii are not favored in the pharmaceutical industry, because there is the disadvantage not only of the non-uniform outer appearance, but also of difficulties in further processing, especially when placing the packages in cartons.
It is desirable to have a method and a stamping tool for fabricating packaging strips with rounded corners of equal radii by which the packaging strips can be stamped out in a waste-free manner without impairment of further processing and where the packaging strips do not present a possible cause of injury.